Named by the law school as the 2015 recipient of the L. Hart Wright Award for Teaching Excellence, Mortenson is active in both international arbitration and domestic constitutional litigation. He has served as arbitrator, counsel, and expert witness in commercial and investor-state disputes under the ICC, ICSID, UNCITRAL, and VIAC rules, and has litigated complex transnational matters in the U.S. courts, including actions involving the enforcement of foreign law and foreign judgments.

Other representative matters include his work as one of the principal drafters of the merits briefs in the landmark case Boumediene v. Bush, which secured the right of Guantanamo detainees to challenge their incarceration, and his role as lead counsel in Caspar v. Snyder, which required Michigan to recognize the marriages of more than 300 same-sex couples. ‎

Prior to joining the Michigan Law School faculty, Professor Mortenson was an associate at Wilmer Cutler Pickering Hale and Dorr LLP in Washington DC and New York, NY. He also served as a law clerk to Justice David Souter on the U.S. Supreme Court. Mortenson received his J.D., Order of the Coif, from Stanford Law School after earning a Bachelor of Arts, summa cum laude, at Harvard College. He lives in Ann Arbor.